Rotary percussion drill



Feb. 5, 952 CRAIG ROTARY PERCUSSION DRILL 2 SHEETS-SHEET 1 Filed Nov]17, 1950 In/en/of 67 zrnesig'rally E. CRAIG ROTARY PERCUSSION DRILLFeb.5, 1 52 2 SI-lEETS-SHEET 2 Filed NOV. 17, 1950 [mn/br Ernesf CrazyPatented Feb. 5, 1952 UNITED "STATES PATENT OFFICE I I '2 ,:5s4,331 IROTARY .EERCUSSION JJR-ILL Ernest Craig,Lakefield, Ontario, CanadaApplication Noveniber 17, 1350, .Seriaili'No. 196;318

6 Claims.' (01. 125 331) 'Ihis invention relates to improvements in.percussion rock drills of the type inwhich a rapidly rotating hammer.is utilized to'strike the drill shank or a tappet interposed betweenthe drill shank and hammer :to thereby effect rapid upon striking whileeliminating destructive .ham-

mer back lash and consequent wearing and chattering, providingsubstantially vibrationless long-life operation.

Another important object is to provide a rugged efiicient drill asaforesaid being capable of effective drilling when-operated'by arelatively low horsepower drive, enabling the inventionto beembodied ina compact relatively lightweight portable drill.

The principal feature of the invention consists in employing a valvingaction to control a hammer mounted in .a "revolving :carrier bodilytranslated about a central axis to lock the hammer against movementunder centrifugal force while remote from the impact position'and to.free the hammer .at impact to deliver its blow through to the steelunder the full centrifugal force and to thereafter freely lift from thesteel.

Anotherfeature consists in providing a timing mechanism to time the blowand ensure operation of the valve to free the hammerat impact. The aboveobjects and features will besreadily understood vfrom the followingdescription taken :in reference to the accompanying drawingsiin' "whichFigure 1 is .a vertical sectional view on the line I-.l of Figure .2through .a percussion drillconstructed in accordance withthis'inventionl' Figure .2 is a vertical sectional view taken throughthe drill at right'angles to Figure ion the line 2-2 of Figure .1.

Figure 3 is a vertical section taken through the cage and hammerillustrating the position of the hammer at impact.

s Figure 4 is a view similar to Figure 3 but showing adifferentposit-ion of the hammer with the cage rotated. Figure 5 is aview similar to Figure 3 showing.

stilla different position of the hammer and cage :rotation. V v

The drill herein disclosed is-generally similar to my co-pendingapplication Serial Number .165,"635 employing a hammer mounted in arecasing by bolts 9.

Z :tatable carrier revolved about the-rotary axis of the drill by atiming mechanism :which correctly times-the blow with the hammer movingwith substantially linear motion in the direction .of the tappet, asexplained in said application.

With reference to the drawings, the drill casing I is shown as acircular casting formed with internal flanges Z and an axiallyoffsetextension '3 having a central bore or passage 4-in which isslidably received a tappet or steel shank 5 to project within thecasing.

Secured to the casing I- are the closing face plates .5 and 1 :heldoutwardly from the flanges 2 by their circular flanges 8 and bolted tothe Each ofthe face plates 6 is formed with a central journal boss illin which is mounted a journal H held in position by "a plate 12.Journalled in each of the journals H is a rotor member :13 :having a hubl4 received within the inner face l-5 of its respective adjacentfa-ceplate abutting the adjacent journal .I l and having' a shaft extension1.6 received 'within the journal. I

The hubs M of the rotor members 13 have secured thereto radial flanges11 formed to receivejournals l 8,-held in position by the plates 20.

Extending trom one of the shaft extensions IG' is-a rotor drive shaft21. 1

The journal's 1180f the opposing rotor members i3 areaxially aligned andjournalled there- @b'e-tweenare cages 22 formed with axially alignedstud shafts .23 received within the journals.

.Moun-tedwith-in :the fiangeB of one of the face plates 5 is aninternally toothed ring gear "24, and the cages 22 are formed at one endwith teeth 25 forming a spur gear which meshes with andis-substantially-one-half the diameter of the ringgear 24 as the rotori3 is rotated.

The *rin-gigear' '24 and the gears .25 form the timing mechanism toitime the blow delivered to the steel 5, as hereinafter morefullyexplained.

. Each ofthecages 22 is provided with'an arcuate recess or slot 26extending through the cage, and mounted in this recess 26 is a hammer 2!free to slide to the position of Figures 1 and 3 where further outwardmovement is limited by the stop 2-8 formed in the cage engagingstop 29of the hammer. The hammer is .formed with a striking face 30 directingthe hammer 'blow through to the steel 5.

Mounted in a recess or slot 3| intersecting the recess .26 is a valve orlooking member 32 having an arcuate hub portion 33 fitting .a circularportion 34 of the slot 31 to support the valve .for

pivotal movement into andzout of contact with teeth and the end plates38 fastened in position by threading onto the threaded ring segments 38of the cage.

In operation the drill is driven from a small motor operating the shaft2 l which in turn drives the rotor l3 carrying the cages 22. The cagesare thus revolved about the axis of the casing and as these cages arerevolved their gears 25 engage the ring gear 24 effecting rotation ofthe cages which serve as the carrier members for the hammers 21.

The cages 22 are of a size'that their gears 25 are substantiallyone-half the diameter of the ring gear 24 and an exact timing isafforded by these gears to bring the cages 22 to the position of Figures1 and 3 each revolution of the rotor with the cages rotating in thedirection of the arrow.

It will be seen particularly from Figure 1 that the position of thehammer 21 is such that under the centrifugal force developed uponrotation of the rotor it is being urged outwardly of the axis of therotor and casing to its striking position against cage stop 28 to effecta blow directed longitudinally of the steel 5 which blow is deliveredwith substantially linear motion in the said longitudinal direction ofthe steel due to the relation of the cage gear being one-half thediameter of the ring gear 24 as explained in the aforesaid applicationSerial No. 165,635.

Thus as the rotor is driven and the cages rotate the hammers 21 willimpart a succession of effective hammer blows correctly timed anddirected through timing of the cage to drive the steel longitudinally.

Figures 3 to 5 clearly illustrate the function of the valve or lookingmember during rotation of the cage to prevent destructive back lash oithe hammer. In the position of Figure 3, that is, at impact with thesteel 5, the valve 32 is swung to a position so that its stop 35 isclear of the hammer stop 31. Thus at impact the hammer is free to liftfollowing the impact blow sliding upwardly in its recess 26 so thatthere will be no vibration imparted to the cage and rotor.

Following impact and rotation of the rotor and 'cage to clear the steel5 there will still be a centrifugal force acting outwardly of the axisof the rotor to force the hammer against the cage stop 28, thiscentrifugal force gradually diminishing as the cage is rotated to theposition of Figure '4 wherein the centrifugal force will be acting tourge the hammer against the wall of its recess 26.

At this position it will be seen that the valve 32 will have droppedinto engagement with the hammer 21 under its own weight, pivoting aboutits hub portion 33, bringing the hammer stop 31 and valve stop 35 intoengagement, blocking movement from the hammer away from the cagestop'28. a

The valve 32 remains in contact with the hammer through the positionillustrated in Figure 5 wherein the centrifugal force acting on thehammer is urging the hammer away from the 4 cage stop 28. Without theprovision of the valve 32 the hammer thus would be driven against itsback stop every time it is rotated through 180 While being translatedabout the axis of the casing l by the rotor 13.

The pressure exerted by the hammer 21 under the action of centrifugalforce against the stop 35 of the valve binds the valve in itshammerlocking position of Figure 3 and the valve is held in place fromthe position of Figure 3 by this binding action until the cage has beenrotated through another 90 to again bring the hammer extendingsubstantially transversely of 'lash occurring where no valve is presentbut further, very materially increases the life of the cage and'hammerelements in eliminating the back lash chatter.

In the disclosure specific simplified valve :structure is shown but itwill be understood that various forms of valves may be utilized withoutdeparting from the scope of the appended claims.

It will also be understood that the particular form and details of thecasing and hammer may be varied within the spirit of the invention.

What I claim as my invention is:

1. Ina rotary percussion drill, a rotor, a rotating cage eccentricallymounted on said rotor, a hammer slidably mounted in said cage, a steeladapted to be projected into the path of said hammer under revolution ofsaid cage and rotor to permit said hammer to strike said steel, andcentrifugally operated means locking said hammer against movement insaid cage immediately subsequent striking said steel and freeing saidhammer during impact with said steel to lift following striking of saidsteel.

2. In a rotary percussion drill, a rotor revolving about a central axis,means for driving said rotor, a cage rotatably mounted on said rotor torevolve about an axis displacedfrom said'central axis, means eiTectingrotation of said cage in a direction opposite'to and at a greater speedthan said rotor, a hammer slidably mounted in said cage for limitedmovement relative thereto to permit hammer action, a steel adapted to beprojected into the pathof said hammer traced upon revolution of saidcage and rotor as said hammer is urged under centrifugal force to alimit position in said cage to strike said steel, translation of saidcage under rotor rotation carrying said cage away from said steel indirection -opposite to direction of hammer blow, and a centrifugallyoperated locking member mounted in said cage and movable in the plane ofand on a path intersecting with said hammer to lock said hammer againstdisplacement from said limit position following striking of said steeland to free said hammer at impact with said steel to permit saidhammerto rebound.

3. In a rotary. percussion drill, a casing, a tappet member reciprocallyarranged to project within said casing, an internally toothed ring gearmounted within said casing, a rotor revolvably mounted to rotate on theaxis 'of said ring gear, at least one cage carried by said rotor havinga gear substantially one-half the diameter of said ring gear meshingwith the teeth of said ring gear to rotate said cage in oppositedirection to and at twice the speed of said rotor, a hammer carried bysaid cage and mounted for movement relative said cage to permit hammeraction, the

, relation of said ring and cage gears being timed with said steel topermit said hammer to rebound.

4. In a rotary percussion drill, a rotor revolving about a central axis,a cage rotatably mounted on said rotor to revolve about an axisdisplaced from said rotor axis, a, steel slidably supported in saidcasing to project therewithin, a hammer mounted in a slot in said cagefor movement relative said cage, timing means driving said cage uponrotation of said rotor to locate said hammer upon rotor and cagerotation to. strike said steel while urged under centrifugal force inthe direction of said steel, a locking member pivoted on said rotor toswing about an axis parallel said rotor axis under centrifugal forceunder rotor rotation in an arc co-planar with and intersecting the pathof movement of said hammer, said locking member being located withrespect to said hammer and with reference to said rotor axis to lieoutwardly of and urged away from said hammer preceding impact and to lieinwardly of and urged into contact with said hammer following impact,said hammer and locking member being formed with co-operating surfacesto lock said hammer against movement relative said cage with saidlocking member urged into engagement with said hammer.

5. In a percussion drill, a, casing, an internally toothed ring gearmounted within said casing, a rotor mounted to rotate on the axis ofsaid ring gear, at least one cage of substantially one-half of thediameter of said ring gear eccentrically and rotatably mounted on saidrotor and provided with a gear of a diameter equal to cage diameter andmeshing with said ring gear, means for revolving said rotor to drivesaid cage through said ring gear at twice rotor speed, a hammer carriedby said cage and having a striking face moving in a substantially linearpath under rotor and cage rotation, a tappet reciprocally arranged toproject within said casing, the timing of said ring and cage gears beingarranged to bring said hammer face against said tappet While moving withsubstantially linear motion in direction of said tappet, said hammerbeing mounted for movement relative said cage upon striking said tappet,and a locking member locking said hammer against movement followingimpact with said tappet and freeing said hammer at impact to rebound.

6. In a percussion drill, a casing, an internally toothed ring gearmounted within said casing, a rotor mounted to rotate on the axis ofsaid ring gear, at least one cage of substantially one-half the diameterof said ring gear eccentrically and rotatably mounted on said rotor andprovided with a gear of a diameter equal to cage diameter meshing withsaid ring gear, means for revolving said rotor t drive said cage throughsaid ring gear at twice rotor speed, said cage having a slot thereinopening to the periphery thereof, a hammer mounted in said slot forrelative movement relative said cage, a tappet reciprocally arranged toproject within said casing, the timing of'said ring and cage gears beingarranged to bring said hammer against said tappet while moving in adirection substantially aligned with the longitudinal direction of saidtappet, and a centrifugally operated locking member mounted in said cageto swing about an axis parallel said rotor axis under centrifugal forceunder rotor rotation in an arc co-planar with and intersecting the pathof movement of said hammer, said locking member being located withrespect to said hammer and with reference to said rotor axis to lieoutwardly of and urged away from said hammer preceding impact and to lieinwardly of and urged into contact with said hammer following impact,said hammer and locking member being formed with co-operating surfacesto lock said hammer against movement relative said cage with saidlocking member urged into engagement with said hammer.

ERNEST CRAIG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,579,840 Rasch Apr. 6, 19261,598,090 Larocca Aug. 31, 1926 1,725,212 Schneider Aug. 20, 19291,770,656 Nielsen July 15, 1930 1,827,611 Bryan Oct. 13, 1931 2,022,546Martin Nov. 26, 1935 2,506,736 Oschwald May 9, 1950 2,515,616 ThomasJuly 18, 1950

